Question 1

What is the term that describes the natural variations in a gene that create no adverse effects on the individual and appear frequently within the population?

Accepted Answer

Polymorphism refers to one of multiple variations of a gene's sequences, which explains why human beings are distinctly different from one another.Autosomal dominant refers to genetic inheritance when an allele on an autosome presents a phenotype, whether a single copy of the allele (heterozygous) or two copies of the allele (homozygous) are present.

Question 2

The 677C>T variant of the MTHFR gene may increase the risk of which disease?

Accepted Answer

The 677C>T variant of the MTHFR gene results in an accumulation of homocysteine, which is a risk factor for cardiovascular disease.

Question 3

Within a strand of DNA, which of the following nucleotide base pairings is possible?

Accepted Answer

In DNA, only two potential base pairings are possible: adenine with thymine and cytosine with guanine.In RNA, uracil may take the place of thymine to be paired with adenine.

Question 4

Which area of study focuses on the identification and understanding of the function of the end products of the genes within the human genome?

Accepted Answer

Proteomics focuses on studying the proteins produced by genes.Metabolomics focuses on the study of cellular metabolites that may be useful in the monitoring of disease progression.Nutrigenomics studies the influence of nutrient and other food factors on the expression of genes.Genomics is the all-encompassing study of genes and proteins and their relation to disease, including the influences of environmental factors.

Question 5

Among which types of inheritance have no nutrition-related disorders been identified?

Accepted Answer

Y-linked disorders are associated with males, but no specific nutrition-related disorders have been associated with Y-linked inheritance.Nutrition-related autosomal recessive disorders include inborn errors of metabolism.An X-linked dominant nutrition-related disorder is fragile X syndrome, a type of mental disorder susceptible to folic acid deficiency.X-linked recessive nutrition-related disorders include nephrogenic diabetes insipidus and adrenoleukodystrophy.

Question 6

Which of the following may promote a change in a DNA molecule affecting gene expression without changing the nucleotide sequence?

Accepted Answer

Genomic imprinting refers to the process by which a change in the DNA results in a phenotype influenced by whether a gene variant was inherited from the mother or the father.Mutations or gene variants are changes in the nucleotide sequence.A single nucleotide polymorphism results in a change in the nucleotide sequence, but by only one nucleotide.

Question 7

Which of the following is the area of DNA where binding of regulatory proteins signals the start of transcription?

Accepted Answer

The response elements are the sequence of nucleotides in DNA that serve as the binding site for regulatory proteins such as transcription factors.The binding of regulatory proteins changes the conformation of the promoter region, increasing or decreasing the ability of DNA polymerase to bind and start transcription.Intervening sequences are long stretches of nucleotides that make up most of the DNA structure and are found between genes.

Question 8

Nutritional components of food affect genetic expression by acting as ligands for peroxisome proliferator activated receptors (PPAR).Which disease may NOT be positively affected by this nutrigenomic relationship?

Accepted Answer

PPAR transcription factors function in lipid and lipoprotein metabolism, glucose homeostasis, adipocyte proliferation, and foam cell formation.Omega-3 and omega-6 fatty acids serve as ligands for PPARs, and as a result, potential beneficial effects could result in reduced expression of type 2 diabetes mellitus, atherosclerosis, and obesity.Research connecting nutrigenomics to cancer presently is investigating relationships to detoxification factors.

Question 9

The purpose of the Genetic Information Nondiscrimination Act (GINA) is to

Accepted Answer

Many legislators and legal experts believe the Americans with Disabilities Act sufficiently protects against discrimination, but as an added measure of protection, the GINA was passed by Congress and went into effect on November 21, 2009.GINA defines genetic testing and genetic information, bans discrimination based on genetic information, and penalizes those who violate the provisions of this law.Consumers and health care professionals can feel comfortable in adopting this new service.

Question 10

Phenylketonuria is what type of genetic disorder?

Accepted Answer

PKU, tyrosinemia, maple syrup urine disease, and other metabolic disorders known as inborn errors of metabolism result from autosomal recessive disorders.Examples of nutrition-related conditions that are autosomal dominant disorders include Albright hereditary osteodystrophy and familial hypercholesterolemia.One nutrition-related X-linked dominant disorder is fragile X syndrome.Diabetes insipidus and adrenoleukodystrophy are examples of X-linked recessive disorders with nutritional implications.

Question 11

Approximately how many nucleotides make up human DNA?

Accepted Answer

When mapping of the human genome was completed in 2003, human DNA was determined to consist of 3 billion nucleotides.

Question 12

In regard to nutritional assessment, which of the following will nutrition professionals need to be able to read to identify a patient's potential susceptibility to diseases?

Accepted Answer

Whereas the genotype refers to the patient's unique genetic makeup, the phenotype is the measurable expression of a gene.The genotype can provide the information that the patient may be susceptible to a particular disease, depending on the influence of specific food components and other environmental factors.If the disease of concern became present, this would be the phenotype expressed.A karyotype is a visual display of chromosomes.Genomic imprinting refers to the process by which a phenotype is influenced by whether a gene variant was inherited from the mother or the father.

Question 13

In genomics, "SNP" refer to

Accepted Answer

An SNP is a single nucleotide polymorphism, which results from the inclusion or deletion of a single nucleotide, thus affecting promoting a variation in DNA.An SNP can affect the sequencing of proteins by transcribing for a different amino acid in the protein sequence.Sex-linked penetrance of a disease within a population is more associated with chromosomal differences as opposed to individual nucleotides.Restriction endonucleases are the enzymes used to cut DNA to extract a nucleotide sequence.

Question 14

What syndrome results from inheriting two copies of a deletion in chromosome 15 from the father?

Accepted Answer

The difference between Angelman's syndrome and Prader-Willi syndrome is the source of the inherited abnormal alleles.When both are inherited from the father, the result is Angelman's syndrome.When both are inherited from the mother, then Prader-Willi syndrome is the result.Williams syndrome results from a deletion of chromosome 7.Down syndrome results from presence of an extra chromosome 21.Klinefelter syndrome results from an extra X chromosome.

Question 15

Which type of disorders are the most common of the Mendelian inherited disorders?

Accepted Answer

Autosomal recessive diseases are the most common as two copies of an abnormal autosomal allele are necessary for the phenotype to be expressed.Both autosomal and X-linked dominant diseases only need one abnormal allele for expression to occur.An X-linked recessive condition could only occur in a woman if she inherits two copies of the recessive trait.Because males only have one X chromosome, if the recessive trait is present, it will be expressed.

Question 16

During protein synthesis, when are introns removed?

Accepted Answer

After transcription results in mRNA production, the mRNA must undergo preparation for translation processes within the endoplasmic reticulum.Among these posttranscriptional processes are the removal of introns, the capping of the 5-prime end, and the addition of a poly-adenosine tail to the 3-prime end of the mRNA.After the protein is produced during translation, posttranslational processing involves the change in the protein to its active form.

Question 17

What is the effect of a silent mutation on DNA?

Accepted Answer

A silent mutation is a gene variant that has no effect on DNA function.The term "mutation" tends to refer to a genetic difference that results in a harmful effect."Gene variant" refers to a genetic difference that may result in a difference, but this difference is not necessarily harmful.

Question 18

Which of the following is a syndrome caused by extra chromosomes?

Accepted Answer

Down syndrome is also known as trisomy 21 because an extra chromosome 21 is present.Williams syndrome is a condition resulting from a missing chromosome 7.Angelman's and Prader-Willi syndromes both involve missing chromosome 15.

Question 19

In protein synthesis, what subcomponent of DNA directs the inclusion of a specific amino acid within the protein?

Accepted Answer

Whereas a gene is the sequence of nucleotides that code for a whole particular protein, a codon within the gene is a three-nucleotide sequence that specifies the individual amino acid included with the protein.The exon is the sequence of nucleotides that corresponds to the sequence of amino acids within the protein.The exon is made up of codons.An intron is a sequence of nucleotides that does not code for amino acids, and these are interspersed between exons.

Question 20

What is the term that describes a gene that is present but not expressing a particular phenotype?

Accepted Answer

Reduced penetrance refers to when a person has the genotype that does not express as the phenotype.This concept is usually applied to the genetic inheritance of disease, such as when the pedigree of a disease is tracked though a family history.Dominance refers to the phenotypic expression of a single allele, whether it is associated with an autosome or a sex-linked chromosome.Linkage refers to how genes are sequenced with others in the DNA strand.

Quiz 5: Assessment: Nutritional Genomics